Effects of bright incandescent light on seasonal and nonseasonal major depressive disorder.

Previous research has indicated that exposure to bright fluorescent light can benefit clinically depressed individuals. The present study, a 1- to 2-week open trial of bright (greater than or equal to 2,000 lux) incandescent light with seasonal (fall/winter) and nonseasonal depressives, produced a therapeutic effect on seasonal depression, as measured by three criteria for recovery: final score on the Hamilton Rating Scale for Depression (HRSD) less than 10; final HRSD score less than or equal to 50% of pretreatment HRSD score; no longer meets DSM-III criteria for major depressive disorder. Phototherapy was not effective in the nonseasonal patients, whose functioning was more impaired than that of the seasonal subjects even before the trial. No adverse effects were observed in any patient.